JP2011510538A - Channel assignment in DECT telecommunications system - Google Patents

Abstract

  A method for wireless digital radio communication with a first number K of channels between the second number A user devices is put into practical use. All A user devices can listen to the same listening channel. For outgoing call communication, a limited number of B channels are used. Communications on these channels are sent to all A user devices on the listening channel. A communication device using this method includes at least one fixed base device (1) and at least A handsets (2).

Description

  The present invention relates to a method for performing wireless digital radio communication between a second number A user devices on a first number K channels.

  The invention also relates to a communication device.

  Wireless telephones are used for many different practical applications. For example, these applications occur at home to circumvent the restrictions on the telephone receiver code. They also occur in industrial and military applications. In the latter two cases, several people each have a communication unit or handset relayed to the same base device, often allowing conversations between them.

  One standard adopted as wireless telecommunications is DECT (Digital Enhanced Cordless Telecommunications). This standard was established in 1992 and has been revised many times since then. The range of this system is about 50m indoors and about 300m outdoors. The DECT system operates on a 10 millisecond time window that is divided into 24 time slots (ie, shorter and well-defined time intervals). Half of these can be used for transmission and half can be used for reception. It can also be expressed as the system uses 10 different frequencies and together they build a system of up to 120 channels. In practice, different frequencies are adopted for “frequency shopping” determined by the system, and the frequency that enjoys the best reception conditions at that moment is used first. As a result, there are actually twelve different channels, which means that it has been possible to relay up to twelve handsets to the same base station that functions as the central nerve of the system. The base equipment checks each channel in a rapid sequence and retransmits possible signals to all other channels on which the handset is relayed. Existing systems perform well in a sense, are well rehearsed to integrate with hearing protection, for example, and are ideal for use in small group communications. However, the operation of current systems using this standard has certain drawbacks. Since the base station transmits the same signal up to 12 times, this method of operation requires considerable energy. This drawback is particularly acute when the base station is battery powered.

  Since up to 12 handsets can be used with each base station, the size of the group that can freely communicate with each other within the group is limited.

  The present invention seeks to reduce the energy consumption of the system while developing a prior art within the framework of an existing standard so that a large number of handsets can be relayed to the same base station. With the goal.

  The purpose underlying the present invention is that the method enabled by the introduction allows all A user devices to hear one and the same listening channel, while a limited number of B channels are It would be achieved if utilized for outgoing voice communication sent to all A user devices on the listening channel.

  With respect to a communication device, the object of the present invention will be achieved if the communication device uses the method according to the foregoing disclosure and includes at least one fixed base device and at least several A handsets.

1 is a schematic diagram of a system comprising a base device and a plurality of handsets. FIG. 6 is a schematic diagram of a time window and frequency. It is a figure which shows the sequence of a time window. FIG. 2 is a schematic diagram of channels included in the system.

  The present invention will now be described in more detail with reference to the accompanying drawings.

  FIG. 1 illustrates a schematic diagram of a communication system according to the present invention using the DECT standard. The system includes a base device 1 and a plurality of handsets 2. The base device 1 and the handset 2 communicate with each other via a radio wave 3 that moves in the direction from the base device 1 to the handset 2 and in the opposite direction. According to the DECT standard EN 300175, radio waves use 10 different frequencies from 1880 to 1900 MHz. Despite being novel, the device and method of the present invention is still compatible with existing DECT standards. As with many frequencies and frequency bands corresponding to the standard, the system also uses a 10 ms long time window, with 12 time slots being used for transmission in each time window, and 12 time slots. Is used for reception. The total number K of channels is 12.

  The novel function of the system and method according to the invention is that all handsets 2 relayed to the base device 1 do not have their own listening channel as in the previous cases, but one single channel. To listen. As regards communications originating from the handset 2, i.e. when the user equipment of the handset 2 wishes to send a call, there is no fixed channel assigned to each handset 2 for this purpose. Instead, several B call channels are allocated to the user equipment as needed. When the system is started, the channel becomes user until all B number of available call channels are allocated, such as the first user device is the first channel and the second user device is the second channel. Given to the device. In the preferred embodiment, this relates to nine different call channels. When an additional user device, ie, several B + 1, wants to use the call channel, the user who has the call channel but has been disabled for the longest time abandons his call channel. Instead, this is assigned to the new speaker. However, a user who is disabled and abandoned his call channel can still hear all communications on the shared listening channel, and such channel is assigned to him whenever he wants to use the call channel. In that case, another user who has been disabled for the longest time at that time will abandon his call channel.

  This is in principle a problem of the prior art according to the DECT standard, but for the sake of completeness, the channel structure of the system will now be described.

  FIG. 2a shows how the system implements a time window 6 divided into a plurality of time slots 7, where transmissions are performed at different frequencies. In the preferred embodiment, the number of frequencies corresponding to horizontal row 4 in the figure is ten. A series of time slots that can be used for digital information transmission, for example voice, corresponds to the vertical column 5. In one preferred embodiment, the number of time slots 7 is 12, and the length of one time window 6 is 10 milliseconds. FIG. 2a illustrates twelve time slots 7 used for transmission as a channel and twelve time slots 7 used subsequently for reception. The 10 millisecond time window 6 is repeated one by one, and the time frame 7 representing one channel uses only a part of the total length of the time window 6 and is therefore very short, for example in a digital manner. Digital information that is stored voice can be transmitted very compactly over such channels. Therefore, the sound quality of the voice extracted in a time longer than the length of the time slot 7 is very good.

  The time window 6 is 10 milliseconds long and includes 12 time slots 7 for transmission and reception. The system itself goes back and forth between different frequencies in a way that, by a pre-determined standard, the frequency that enjoys the best transmission conditions at that time is used. Therefore, it is not necessary for the user apparatus to individually adjust any effective frequency, and it is sufficient to register the handset 2 with the base station 1.

  Unlike frequency, time slot 7 corresponds to the same channel, so the assigned time slot 7 will be retained by the same user device over time. Only when all channels are assigned to user equipment and additional user equipment wants to use the channel for calls, the user equipment that has been disabled for the longest time will abandon its own channel and use the shared sum channel. You can only listen.

  FIG. 2b illustrates a schematic view of a plurality of time windows 6 going one by one in the sequence. The time window 6 includes a plurality of time slots 7, each corresponding to one channel. The frequency is ignored in FIG. 2b because the system itself keeps track of frequency changes.

  Each time slot 7 always corresponds to the same channel, and in FIG. 2b, the second time slot 7 from the left of each time window 6 corresponds to one invalid channel. The third time slot 7 from the left of each time window 6 corresponds to a conversation completed after three time windows 6. The fifth time slot 7 from the left has content in the first two time windows 6 but is silent on the corresponding channel during the third and fourth time windows 6.

  FIG. 3 illustrates a functional diagram of the outgoing channels 9a, 9b, 9c including the channels 8, 9a, 9b, 9c that can be used to transmit a call to the base device 1, and the sum channel 9a and the emergency channel 9b. . In the schematic diagram of FIG. 3, the structure of the system at the time frame level is ignored, and emphasis is placed on how the user device perceives the system.

  In the preferred embodiment, the number of incoming call channels 8 is nine and nine different user devices can use them simultaneously. The base device 1 sums the incoming signal, i.e. the call on the incoming channel 8, and the summed signal is sent to all user devices in the system, i.e. all user devices that have access to the call channel 8 at any time. Transmit to a single channel 9a that the user device listens to. The shared listening channel 9a is also qualified as a sum channel or a conference channel, respectively. Since transmissions from the base device 1 occur in only one channel rather than each user device channel, transmission according to the preferred embodiment implies a much greater reduction in energy consumption than previously possible.

  The handset 2 can gain access to the call channel 8 whenever necessary. A user device that has been inactive for the longest time is “pushed off” as a calling user device, and then has access only to outgoing channels 9a and 9b until the user device wants to talk again.

  The system, ie the base unit 1 automatically handles the distribution of the incoming call channel 8, and the user unit presses a button (push-to-talk (PTT)) etc. or starts talking (voice controlled talk function) With this, there is no need to send an intention to make a call and do anything else. Automatic handling of the talk channel and constant interception by all other user equipments heard on the sum channel 9a always have access to both the listening channel and the talk channel, ie "full duplex". Gives all user devices a sense of being.

  The emergency channel 9a is common to all user devices of the base device 1, but is unidirectional transfer, meaning that the user device listens only on this channel. In many cases, the emergency channel 9b is common to a plurality of base devices 1 operating in parallel with each other. One prerequisite is to place them very close to each other so that the base stations can synchronize (ie they must be placed within each other's range). Synchronization of two base stations positioned within each other's range is rehearsed to be performed automatically when the base stations establish contact with each other. Each base device or user device of the base station 1 is included in a different group and usually does not communicate with each other. Since the emergency channel 9a reaches all user devices at the same time, it is suitable for emergency messages that must be immediately distributed, such as fire alarms and explosion hazards.

  Finally, FIG. 3 is a technical channel, mainly a “handover” channel, ie, one user equipment from one first base equipment or base station 1 area to another base equipment or base station 1 An additional outgoing channel 9c is illustrated which is used as a channel used for call handover (handover) when moving to an area.

Description of alternative embodiments.
As described above, the present invention has been described with a plurality of incoming channels 8 and a plurality of outgoing channels 9a, 9b, 9c, respectively. Of course, the number of channels 8, 9a, 9b, 9c employed in both directions may vary. At the same time, it can be considered to apply the present invention to several telephone standards other than the DECT standard mentioned for introduction.

  Another way to resolve channel assignment to user equipment is to completely shut down each outgoing voice channel that is no longer in use. Then all available outgoing voice channels are closed and one of the available channels is activated when a new user device wants to talk. This variation of the present invention enjoys the advantage of completely shutting down a call channel that is not actually in use, and consequently eliminating the required power. Furthermore, no algorithm is required to determine which user equipment is invalid for the longest and should be abandoned. However, one drawback is that enabling the call channel takes a certain amount of time, typically 0.5 to 2 seconds, which is sometimes perceived as inconvenient.

  A program for a plurality of incoming call channels 8 can be changed to be an outgoing channel. These additional outgoing channels can be used in the same way as the summing channel 9a described above. Accordingly, it is possible to establish subgroups each having access to the sum channel on the same base device or base station without departing from the scope of the present invention.

  The present invention may be modified without departing from the scope of the appended claims.

Claims (9)

  A method for performing wireless digital radio communication between a second number A user devices on a first number K channels (8, 9a, 9b, 9c), wherein all A user devices Are allowed to listen to the same listening channel (9a), while the limit number B channels (8) are transmitted to all A user devices on the listening channel (9a) A method for wireless digital radio communication, characterized in that it is used for communication.   When the number B latest user equipments of the outgoing voice channel (8) are assigned to one such channel, and when one additional user equipment requests the call channel (8), the Method according to claim 1, characterized in that (B-1) latest user devices hold their channels (8) and freed channels (8) are allocated to the new user devices. .   After the user device that wants to talk is initially assigned to the outgoing call channel (8), the user device completes the voice communication of the user device, and finally any number A users use it again The method according to claim 1, characterized in that the outgoing call channel (8) is closed until it is desired to do so.   4. The message according to claim 1, characterized in that an urgent message, a so-called emergency message, is transmitted on a single channel (9 b) common to a large number of user devices of A or higher. The method described in 1.   Method according to claim 4, characterized in that the emergency message channel (9b) is transmitted from two or more fixed base units or base stations which are initially synchronized with each other.   The method according to claim 1, wherein B ≦ A.   Communication device using the method according to any one of claims 1 to 7, characterized in that it comprises at least one fixed base unit (1) and at least A handsets (2).   Communication device according to claim 7, characterized in that it comprises at least two fixed base devices (1) that can be synchronized with each other.   Communication device according to claim 7 or 8, characterized in that at least one of the handsets (2) has voice control.

Images